If your mattress surface runs hot, no sheet or comforter can fully compensate. Breathability at the base layer determines how quickly your bed can release body heat after each sleep cycle.
For dense memory foam beds, consider topper strategies and airflow adjustments first. Good references include ViscoSoft Active Cooling Topper, Saatva Graphite Topper, GhostBed Topper, and Purple Mattress Topper.
Use this page with gel infusion fundamentals, graphite and copper guide, bedroom airflow setup, and building a cool bed.
Then refine upper layers using best cooling sheets and best cooling comforters.